1. Field of the Invention
The present invention relates to terminal blocks for electrical circuits and particularly to terminal blocks which may be programmed and/or reprogrammed in the field to interconnect a plurality of input and output circuits. More specifically, this invention is directed to the establishment of electrical connections between individual input circuits and individual output circuits in accordance with a predetermined program and to facilitating the establishment of a different arrangement of circuit connections if and when dictated by a revision of the program. Accordingly, the general objects of the present invention are to provide novel and improved apparatus and methods of such character.
2. Description of the Prior Art
While not limited thereto in its utility, the present invention has been found to be particularly well suited for use in telephone and security systems wherein individual input lines are to be connected to one or more output lines pursuant to a predetermined pattern or program. By way of example, in a hard-wired fire alarm system it may be desirable to connect a single incoming line from a sensor device to outgoing lines connected to annunciators at a plurality of guard stations. Connector or matrix blocks having the capability of establishing connections of the type briefly described above are known in the art as exemplified by the disclosures of Rosenberg et al. U.S. Pat. Nos. 3,437,740, and 3,539,873.
Prior art matrix blocks have been possessed of a number of inherent deficiencies. The principal deficiencies have resided in the fact that prior matrix blocks have not been repairable in the field and have either been difficult or impossible to program and reprogram in the field; reprogramming usually requiring the unsoldering and resoldering of "jumpers". A second prevalent deficiency of prior art matrix blocks has resided in their construction which placed terminals and other components in an exposed location where they have been readily subjected to accidental damage or the undesired establishment of an open or closed circuit condition by service personnel working on nearby equipment. Since prior art matrix blocks have not been field repairable, this has posed a major problem from an economic viewpoint. Still further disadvantages of prior art matrix blocks resided in their comparatively high initial cost and large size which was not suitable for rack mounting.